Jerrold J. Katz offers a radical reappraisal of the -linguistic turn- in twentieth-century philosophy. He shows that the naturalism that emerged to become the dominant philosophical position was never adequately proved. Katz critiques the major arguments for contemporary naturalism and develops a new conception of the naturalistic fallacy. This conception, inspired by Moore, explains why attempts to naturalize linguistics and logic, and perhaps ethics, will fail. He offers a Platonist view of such disciplines, justifying it as the best explanation of their autonomy, their objectivity, and their normativity.